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Everything posted by radulescu_paul_mircea

Hello guys,
I was triyng to build a pair of Othorns before Christma2s but my plans didn't go that well because it seems I can't find nowhere to buy ( for now) a pair of 21's fron B&C or 18sounds.
So, now i still want to build a pair of subs and I was looking in other projects. First I saw the Xoc's Th18 and then the Keystone which I like it more because it is easier to build and it kinda looks cool
When I compared the Spl results from Walter's measurements I saw it can reach around 130 dB/1m GP and has a FR down to 35Hz.same with Th18. Othorn on the other hand goes 8Hz lower and it reached a max Spl of around 137 dB/1 m. Also, on the specs of TH118 from Danley they say it has 137 dB cont. Taking into acount the compression for the driver in the Keystone, at 1800 watts as Walter measured that seems to be a very real, easy to verify value. Also I trust Ricci's measurements so if he says his sub gives that Spl, it does.
So, now, the questions:
1. Is the 21sw152 driver that much more powerfull to gain 6 dB more at higher freq than the 18sw115, even if it is tuned 8Hz lower
2.where does Danley take their nubers from? Because from what i see, the xoc1 design is preety much the same and it has around 6 dB less continous output
3. Is there a company that takes into account power compressio? Because I can't find any
4. Which should be better in a small space af around 300sqm beetwen 2 Keystone or 2 Othorn both with 18sw115.
Paul

I didn't test it after all , because I changed the 18"s with 21"s to use them in my own designs. I don't want to use that design anymore, it's better to use my own The difference though is huge, the efficiency and thermal stability are way higher than those of the SW115. I'll use the 18 IPal in one of my other designs and after that I'll use the 18Sound where normal drivers are needed.
And the 21" Ipal is so powerful compared to anything else, the sound is so much better!

For me, it's a strong hiss from the speaker. And also some high pitch sound. Also, when the signal is very very low, the sound is very similar to that one produced by a rubbing voice coil, but this happens with only this amp

If you have the module, can you please tell me how noisy is it? Mine are terrible on this spec, the amp generates a very powerful hiss and buzz through the driver. I've even disconnected the coolers to see if the interference is from there but nothing happened.
Also, I haven't managed to connect it with power control manager software, I've tried it with two PC's and with 2 different serial adapters.
I don't know if you saw that they have changed the specs on this one. They reduced the max Voltage from 195 to 180 peak, the current also and the power is now 4500 watts at 2 ohms. In the software the maximum power is 5000 VA PK, current is 100 and true power is 700 watts over a maximum of 3 seconds. This means it is way lower than a channel from a K20 and TBH, if a SpeakerPower SP 6000 is capable to sustain that power for 4 seconds and then to drop to 2400 watts , that is way more that what this one is capable of.

If you leave the response as it is , you'll see that the impulse response is truncated at +500 Ms from ref time. If you use the tools to change it at 125 Ms and to increase the zeros before ref to keep the resolution, you'll find that the response gets clearer. This is because I was surrounded by solid buildings and their reflexions were very powerful

I used about 28 volts for these measurements , but the voltmeter wasn't very precise so until I get a better weather to be able to take another reading with a new ,much better meter, I'll settle for what I have now.
I have used one FP14000 clone for them , and adding another dual 18, 3 drivers per channel, I managed to pop a 16A breaker at 230 V. It is quite power hungry

They 1, 2, 4 in a 2 by 2 stack and 4 in a vertical line stack.
The measurements were taken at 0 deg, 90 deg ,135 deg and 180 deg from axis on ground. The noise floor wasn't that high. It was lower than 60 dB for most of the time and when the wind was harder, I paused the measurements until it settled.

Hello everyone,
Here you can find cool information about a concept for audio reproduction.
I was following the work of Holoplot company from Germany for a while and I tried to learn more about the way they work. Now I got my answer from Mr. Charlie Hughes, who is a consultant for the concept in the link
https://www.jambase.com/article/madison-square-garden-co-open-concert-changing-msg-sphere-arena-las-vegas
holoplot.com
http://www.holophony.net/

For anyone who wants to see the measurements for the directivity of 1,2 and 4 single 18" subwoofers in different configurations, on and off axys, you can access my Drive account and download the zip with REW measurements. Where there is a V, it means vertical possition
You would need to change the Impulse response windowing to Left Window Tukey 0.25 400 ms, Right Window Blackman-Harris 7- 150 ms and Ref. T is left in place for each sweep.
https://drive.google.com/open?id=15MmO5qj9v1RLZfO1_BYkUIAf6MDLi8M2
I hope it works.

https://www.facebook.com/groups/733449990043427/?ref=group_header
This is an awesome group on Facebook and I've been posting there for a while. Some of my measurements can be found over there and many other discussions mostly for pro audio.
You can find manufacturers there , like Brandon Heinz (from Renkus Heinz) Dave Millard, representative from full far audio, Sean Hennessey and some others.
Please, feel free to join!

Testing the Directivity index of different configurations of subs and summation. Wow!! With only 4 single 18 in a square stack, one gets a huge front to back directivity.
I've tried a single, double vertical, double horizontal, 4x 2 by 2 stack, 4 tall and I forgot about 4 horizontal but I was already frozen by then.
On axys , 90 deg, 135 and 180 degrees off axis, at 1, 2, 4 and 10 meters.
Well calibrated mic , ECM8000 with absolute SPL calibrated from a B&K 2270 to 0.1 dB ( hard work to do that unfortunately, I'll get a new mic very soon), Focusrite Scarlett 2i2, REW with loop, 20 meters from any wall, sweep measurements and RTA. I also did CEA2010 bursts , maximum SPL and loads of fun!
Plus some playing with a closed enclosure loaded with dual 21Ipal isobaric series.
Amplifiers were a FP14000 clone, one Crown XLS 2002 and one Martin MA2.8.
I'll need to find a way to post pictures here, I have some graphs, I have 130 measurements , I'll make some plots , some excel work on them.
@Ricci yes I am using ABEC 3 but barely. It is way to complicated for now and I don't pretend I am getting any easy progress. I have an Akabak script on my older laptop (it doesn't run on Windows 10) that I could copy and post or send to PM. It is not very detailed but with the additions I managed to get a higher Directivity and a closer response.

Welcome Moar!! Thanks for the link, it is a very useful tool. I needed that in my life
Playing with it I've been getting very interesting results, some of them really incredible. Even from a single enclosure, the Directivity starts to go forward even at very low frequencies like 40 Hz.
This made me go out in a parking lot with 4 single 18 subs and to take directivity measurements.

Looking at the linearity of the parameters for this driver, I bet it would be an extremely good and musical bass driver up until maximum pressure.
http://www.audioxpress.com/article/test-bench-precision-devices-pd-185n02-woofer

That M-Drive is a true beast, the way it can swing volts and amps is exactly what a driver like M-Force needs. It is not exactly double the IPal though.
@Ricci
,What do you mean, will you get your hands on one? That would be great, to see what it's capable of.
The DPC sensor was firstly made to be installed into the driver dustcap, but the added complexity wasn't worth it on those wavelengths. But still, for it to be able to truly function, it needs to be as close as possible to the acoustic radiator. It can be defeated if the feedback gain is set at -100 dB in Power Control Manager, so if you want to use the amps only on Virtual Transducer without DPC, you can. I haven't tried to use it without connecting the sensor.
@awedio I have tested the IPal module. I own one and I'll add 3 more soon . But go pro audio use

I've managed to get this sensitivity curve when I simulated the acoustic load of the air around the enclosure, as if it would be another waveguide with a very rapid expansion, but acting on the enclosure . In fact that, coupled with some acoustic resistance in the enclosure, higher losses through friction, increased viscosity in the port and enclosure gave me the most similar response.

I'll recommend you to use a single module for both drivers in series. It is more than enough for them. It will exceed the nominal excursion of the drivers at 25 mm at about 20 hz with all losses and nonlinearities accounted for. Also ,the DPC sensor needs to be extremely close to the acoustic center and that's why I think that enclosure is not best suited for this application. You would better use a manifolded enclosure, this way your acoustic center is very close to both diaphragms and the feedback loop gets more accurate. Having 2 modules in this tiny box is a huge waste.
Also ,the M-Drive modules are not available without the motor and this system is hard to get and to implement.

Is there a way of explaining how is it possible that the sensitivity of the speaker to be 107 dB at 100 watts/ 10 meters at 100 hz? I've tried everything to get that sensitivity in Hornresp and Akabak but with no results.i usually get a play response from 40 to 120 hz at about 102 dB. The rising response is not present in any simulations, except if I take into account the directivity increase at higher frequencies , but even with that, I can't seem to duplicate the results.